Motorcycle Repair: 1971 Yamaha Jt1, piston rod, working memory

Question
Well I recently bought a Bike 1971 Yam. Jt1
I think it is a neat looking bike,However:I blew an oil seal on the magneto side so the whole engine was taken apart and seals and gaskets were replaced ,Bearings,piston,rod,rings,And other internal components were all like brand new..The valve <rotary> Disc Is there only one way to install this..Im now getting backfire out of carb almost sounds like an exhaust rumble..
  feels like I am getting more blow out than suction when i PUT HAND OVER CARB AND Kick it over..I also would like to know the right way to set the points gap,cannot seem to locate timing marks other than center of magneto.,,Please Help be as detailed as possible...

Answer
Hi Daniel,

I have no resources for the 1971 JT1. I cannot advise on installation of the rotary disk or other specs. It's too old for me to have a working memory of specs, either. lol

I recommend performing a compression and leak-down tests. Keep searching on-line for JT1 related websites.

Respectfully,
Mark Shively